Leases - Schedule of Right-of-Use Assets and Lease Liabilities (Details) - USD ($) $ in Millions	Mar. 31, 2022	Dec. 31, 2021
Lessee, Lease, Description [Line Items]
ROU lease asset	$ 41.6	$ 42.2
Lease liability	$ 44.8	$ 45.2
Operating lease, weighted average incremental borrowing rate, percent	5.10%	5.00%
HG/BAM
Lessee, Lease, Description [Line Items]
ROU lease asset	$ 7.1	$ 7.6
Lease liability	7.7	8.1
Ark
Lessee, Lease, Description [Line Items]
ROU lease asset	8.1	7.0
Lease liability	8.1	7.0
Specialty Insurance Distribution (NSM)
Lessee, Lease, Description [Line Items]
ROU lease asset	13.3	14.0
Lease liability	14.5	15.2
Asset Management (Kudu)
Lessee, Lease, Description [Line Items]
ROU lease asset	6.4	6.5
Lease liability	7.1	7.1
Other Operations
Lessee, Lease, Description [Line Items]
ROU lease asset	6.7	7.1
Lease liability	$ 7.4	$ 7.8